--  @testpoint:opengauss关键字cluster(非保留)，作为函数名
--关键字不带引号-成功
drop function if exists cluster;
create function cluster(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/
--清理环境
drop function cluster;

--关键字带双引号-成功
drop function if exists "cluster";
create function "cluster"(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/
--清理环境
drop function "cluster";

--关键字带单引号-合理报错
drop function if exists 'cluster';
create function 'cluster'(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/

--关键字带反引号-合理报错
drop function if exists `cluster`;
create function `cluster`(i integer)
returns integer
as $$
begin
    return i+1;
end;
$$ language plpgsql;
/